A semiconductor integrated circuit has come to have various configurations in recent years. Various patterns are arranged on a substrate to be processed in order to form such configurations. When the formed pattern is measured and converted into a numerical form, there has been used a dimensional value measured by a scanning electron microscope (SEM). In this case, there is a limit to how well a pattern having various forms is measured and converted into the numerical form. Accordingly, a method that extracts and evaluates an outline of the pattern from a picked-up SEM image is becoming more predominant. Two-dimensional indices such as an area and a positional deviation can thus be expressed in the numerical form by using the extracted outline.
Precision of the outline becomes very important in the method of extracting and evaluating the outline. In order to increase the precision of the outline, a large amount of outlines are acquired and averaged in the current situation. However, an enormous amount of time is required to acquire the large amount of outlines. Moreover, there has been acquired only an outline that is formed under a desired process condition.